CiiAPTEH. IT.—Al/nrlal T)epnsit.<i and Bloion S'ni(h. 



Deposition of alluvium has taken place along- the whole sea-board 

 of this part of Southern India^ forming a conti- 



Position. 



nuous belt varying in breadth, which, in a west- 

 erly direction, runs up the valleys of the three main rivers, and of their 

 tributaries ; while all along the edge of the sea-ward belt, and occa- 

 sionally further inland, ridges of sand have been formed by the winds 

 prevalent in these localities. 



The alluvium of the Cauvery extends over a very wide area, occu- 

 pying a considerable part of the Trichinopoly 

 Alluvia of the Cauvery. 



district, and by far the larger half of Taujore, 



and it strikes up in a northerly direction to join the alluvium of the 



Vellaur in the South Arcot district. 



The delta commences at the head of Seringham Island, 10 



miles west-north-west of Trichinopoly, where the 

 The Delta. 



Coleroon branches oiF, forming the most northerly 



of the many channels by which the water reaches the sea. Part only of 

 the delta is described in this report,^ the portion which lies south of 

 a line drawn in a westerly direction from a point 5 miles south of 

 Negapatam, in north latitude 10° 40', not having come under examination. 

 The northern boundary of this alluvial valley, beginning at the west- 

 ern limit of the m5,pj is formed by metamorphic 

 Northern boundary. 



rocks, which extend eastward, with a short inter- 

 vening spread of cretaceous rocks, to Kullare, about 9 or 10 miles 

 south of Arrialoor, From this point the cretaceous rocks, succeeded by 

 Cuddalore sandstones, form the boundary ; the latter formation gradually 



* The alluvium is known to exteiid as far south as point Calimere, about 30 miles, with 

 a probable width of not less than 20 miles, formmg thus an area of about 600 square miles 

 in extent, which fairly belongs to the delta of the Cauvery. 



D (M7) 



